Local TV new blows Ardipithecus story
If you don't believe in evolution, you might not want to listen to this next story. Scientists reported this week on a new fossil, possibly a human ancestor, older than Lucy. The good news is, we're not descended from chimps after all. The bad news is, chimps and humans are descended from the same ancestor.
That's a paraphrase of how our local TV news covered Ardipithecus ramidus, the fossil hominid discussed in a series of papers in this week's issue of Science. Read all about it on Carl Zimmer's blog. The TV anchor didn't say which scientists claimed we are descended from chimps, perhaps because no scientist has made that claim. Chimps have evolved over the six million years or so since our last common ancestor, including their split with bonobos. Can we expect the story below on the TV soon?
Startling breakthrough in human genetics! You aren't descended from brother after all, or even from your cousin. You and your brother still have the same parents, and you and your cousin have the same grandparents, though. I hope that doesn't upset you too much.
We don't know for sure that present-day humans are descended from Ardipithecus . It's a reasonable hypothesis, but any hypothesis is, by definition, subject to possible disproof. For example, if we found another fossil that was clearly much more similar to modern humans, dating from the same time or earlier, then we'd conclude that Ardipithecus probably has no surviving descendants.
But this species probably isn't too far from the direct line of descent between our common ancestor with chimps and modern humans. Suppose you wanted to know what your great grandmother looked like, but there was no surviving picture of her. If you had pictures of her sister or her daughter, that would give you some idea, even if all her living descendants are descended from a son.
Of course, much of what we know about our ancestors now comes from analyzing DNA in humans and closely related species. We can figure out when vitamin C synthesis was lost or adult lactose tolerance gained, for example. But we don't yet understand development enough to predict height, foot shape, etc., from inferred DNA sequences of ancestral species. So keep those fossils coming!